Lol, I understand your point but the proper clearence is 0 lash. No offense but i t doesn't take a rocket scientist or a feeler gauge to find 0 lash, lol. The easiest way would be to leave the covers on and find the culprit with a makeshift stethoscope while the engine is running. He can search for his vacumm leak at the same time. If all else fails then he can go back and inspect them all. He can use the feeler gauge when he finds the culprit.